1. Field of the Invention
A system, apparatus and process for practice for the reduction of sodium hydroxide with natural gas in the presence of heat to produce, after quenching, sodium metal as a product of the thermodynamic reaction.
2. Prior Art
The invention is in a system and apparatus for practicing a process where separate flows of a heated liquid sodium hydroxide, oxygen and heated methane are sprayed through a mixing nozzle to strike one another and mix for burning in a burner area of a reactor vessel, with vaporous sodium metal, carbon monoxide and hydrogen gases, the product of that burning that is passed from the reactor vessel for quenching to rapidly cool and liquify the sodium into metal that is then passed to a storage vessel with the carbon monoxide and hydrogen gases passed for discharge or recycling in the system.
Apparatus and processes for refining sodium metal are old in the art, with a recent U.S. patent application Ser. No. 09/262,876 filed Mar. 5, 1997, by one of the inventors being an example of a new system to include a reactor vessel wherein a heated mixture of sodium hydroxide and methane is provided to vaporize the mix into sodium metal vapors, carbon monoxide and hydrogen gas, which mix is then quenched to separate out the liquid sodium metal from the gases, with the liquid sodium then passed for use. Unique therefrom, the present invention provides a nozzle arrangement for spraying separate flows of heated sodium hydroxide, oxygen and methane together in a burner area of a reactor vessel creating a chemical reaction that produces a sodium metal vapor, and carbon monoxide and hydrogen gases, which mix is passed to a quench chamber wherein vaporized sodium metal is condensed to a liquid that is drawn off for use.
Very earlier apparatus and processes are shown in U.S. Pat. No. 342,897 to Castner; U.S. Pat. Nos. 380,775 and 380,776 to Thowless; and U.S. Pat. No. 460,985 to Netto, as examples of systems that utilize a carbonaceous material as a reactive agent, usually carbon in powder form, that is to react with the compound containing sodium or potassium in the presence of high heat to produce free sodium. Such processes have, however, not only required that a number of complex steps be performed to finally produce sodium metal and, unlike the invention, they have generally been single batch processes only.
Additionally, a French Patent No. 603,825, shows sodium metal being reacted with iron in powder form by first vaporizing the mix and then condense out sodium vapor at temperatures below the sodium condensation temperature. Such process has, however, required that it be conducted in a vacuum and that sodium vapors as are produced be removed from a reaction zone and condensed. Further, in the '825 patent, like a later U.S. Pat. No. 2,642,347 to Gilbert, sodium metal vapor is produced from a condensation of sodium carbonate that has been reacted with carbon at a heat of from 1000 degrees C to 1200 degrees C, which vaporization takes place after the sodium metal vapor has been conducted away from the reaction. Condensation in the Gilbert '347 patent utilizes surfaces of steel balls that are maintained at a temperature below that required for sodium vaporization, with vapor contact with the steel ball surfaces condensing sodium metal. The above cited systems are each essentially a batch system, unlike the present invention, that is a continuous system where sodium metal is produced in liquid form and is continuously drawn from a bottom vessel of a quench chamber, and neither involves a use of sodium hydroxide and methane as reactants. Nor do the either of the systems of these patents proved, as does the invention, a novel mixing spray nozzle that directs individual flows of the heated reactants against one another to break the flows into fine particulates, mixing them together in a high heat atmosphere, to react and produce vaporous sodium metal, and carbon monoxide and hydrogen gasses, with the mix then quenched to liquify sodium metal that is then removed for use. With such quenching taken place in a vessel or vessels that maintain a cooled surface, such as a coil receiving a coolant liquid passed therethrough and/or may include spraying of a non-reactive coolant into the vaporous mix as it enters the quench cooler, which quenching condenses out sodium metal from the reactant vapors that is then drained into a storage vessel.
A U.S. Pat. No. 2,930,689 to McGriff teaches a submerged combustion of methane in molten sodium carbonate and includes a separation wall to prevent the combustion gases, water and carbon dioxide, from entering into the reaction of methane or carbon with sodium carbonate. The McGriff process requires an operating temperature of from 1150 to 1250 degrees C, with carbon or methane fed into the hot sodium carbonate, and with sodium carbonate continuously added. The process requires a continuous addition of carbon, preferably coke in powdered form, to perpetuate the reaction. In practice, handling of a solid material, such as carbon, is a disadvantage that is not present in a practice of the invention. Further, McGriff '689 does not include a mixing nozzle or quenching arrangement like that of the present invention, but provides for an immediate reaction at high heat to produce vaporous sodium metal like that of the invention.
While McGriff '689, like the invention, teaches a use of methane as one of the reactants for producing sodium metal, that production is from a molten sodium carbonate, and further, unlike the invention, it requires that carbon, in powdered form, be continuously passed into the reaction vessel. Also, unlike the invention, the McGriff '689 patent provides for burning of the introduced methane producing a high heat in the presence of carbon, with methane fed into hot sodium carbonate and with carbon, as solid coke in powdered form, continuously added for the reaction to proceed. Further the McGriff '689 patent does not deal with problems inherent in quenching sodium metal from a mix of gaseous carbon monoxide (CO) and sodium (Na), and fails to recognize and deal with a back reaction as will occur as the gases cool where sodium metal tends to react with carbon monoxide to produce sodium carbonate (Na.sub.2 CO.sub.3), which problem of back reaction the invention addresses and solves.
Further, a patent to Deyrup, U.S. Pat. No. 2,685,346, like the invention, incorporates a step of quenching of a hot vapor containing a free alkaline metal to cool the alkaline metal to a molten state, and deals with a handling of a back reaction as the sodium vapor is quenched from the carbon monoxide and sodium gases. Unlike the invention, however, the Deyrup '346 patent involves a use of large amounts of tin, must be operated at high temperatures, and, of course, does not involve a mixing spray nozzle arrangement like that of the invention. Also, the Deyrup '346 patent teaches a multi-step process to provide for a quenching of the sodium metal and accordingly, in its operation, it is likely that a large percentage of the collected sodium metal will be lost to back reaction, and further the system of the Deyrup '346 patent is not continuous.